Air charging control



Aug. 16, 194a 5 LE N 2,479,012

AIR CHARGING CONTROL Filed April 12, 1946 IO '2 .A

42 FIG. i 39 as 37 4o INVENTOR.

AMBROSE E. LE VAN ATTORNEY Patented Aug. 16, 1949 ITED STATES PATENT em2,479,012" l AIR CHARGING oomlton I I Application April 12,1946,-Scrlalil lo. 661,899

This inventionrelates to a ,jet pump system wherein a pump deliversliquid from a, wellinto a pressure liquid storage tank, and, moreparticularly, to a devicefor controlling the air contents in the tank. a

In pressure liquid storage tanks onlypartof the space in the tank istaken up by liquid, whereas the upper portion of the tankcontainscompressed air. While the liquid iststanding in-the containeritabsorbs gradually more and more' of the air on-top of the liquid, andwhen liquid is withdrawn from the tank, it carries with itsome of theairso absorbed.

Various devices permittinga small amount of air together with the waterdrawn from the-Well to: be drawn into the suction side of a-pump-areknown and one such device is shown in thePatent 2,291,746 granted toR.N. Nelson etral. "When a pump is first started up, the suction is.abnormally high to provide the-force necessary to put the column ofwater. in the well and the piping in motion and this high suction mayresult in drawing in air at such a rapid ratetthat the pump suction isso reduced that the pump'fails tofill itself with water drawn-upfrom.the wellandbecomes air-bound.

The invention provides forzthe first timeffor:

the admission of air to the suctionside 'ofithe pump only if air isneeded in'the' tank and then only after the suction pressurehasxreached'normal values.

It is an object of this invention to provide afievice capable ofcontrolling the quantity'of airiin' the pressure liquid storagetankingamanner'to replenish the air contents in the tank by:;means of airdrawn into the system in: response-taithe difference between atmosphericpressure :and a variable suction pressure created by .the pumpdelivering the liquid into the tank.

A further object of' the invention. is toprovide.

a device which controls the amount ofair added to a closed tank forstoring liquid'underv pressure. by permitting air to be drawn into thesystembythe liquid flowing from the tank throughz'a venturi passage tothe pump. inlet; the'Venturi-passage being normallyclosed by a valve,said-valve being opened only whenthelevel of liquid in:the storage tankrises above .a. pre-set point and at the same time, the pressuredifferential between the inlet of the pumptan'd the: atmosphere isiless.

into the system .by::means .of .liquid passing iefclaims'. (01. 103-5)through a :llenturkpassage controlled by a valve whenever; an'das:longeaaisaidtvalve is open.

Itiisianother 'obiect 10ft the: inver-itionl toprovide in a jet pumpsystem, wherein apumpdelivers liquid from aiwell into za pressureliquidstorage tank, a 'by-pass leading fromithe tank to the suction rsideofthe ;.pump z'forsthe admission of finely .dispersedtalr {particles intothe liquid system, said :bya-pass .;including.; a Venturi .sectionwherein the --statlcliquidgpressure of the liquid flowing therethroughtis reduced; to i a subatmospheric valuezto suck iniatmospheric'air-whena valvecontrollingthis Venturi rsection is open, said valve beingopenablei only when unlocked from a mechanismiresponslve l-to variations"of the liquid level. in thetankaniifiso; preconditioned for an opening:movement, willi-beopened when the suctionpressure .oflthegpumpiiszoriallsbelaw a presetvalue. Y

A further object of the invention is to provide inandevicee for.controllingihe air contents in a pressure liquid-storage.tank whereinair isdrawn into it-he system iby means :of pa liquid passing throughvatventurhpassage. controlled by a valve,

.azdiaphragmlior .clcsing said valve responsive to the difierence ofatmospheric pressure and the suction pressureecreated by-the pump and aspring capable of :.opening .the valve against the .diaphragm pressurewhen said esuction pressure is less. than apre-set amount.

Y, :StilL another object .of gthe-invention. is .to operatively connectthe valveccontrolling. the aforewhere well water is drawn up from thewellzby an eiectormlacedinear the'bottomoi thewell, and in V which:

Fig. '.-1 shows :in a ;:dia,-grammatic :elevational view, partlyinesection ioneg'form :ofsa jet pump system; and t I i ;:Fig. .2, eat :alarger scale, n-a vertical section :of 7

thaairrcontrollingdevlcepmper.

. In thezdnawing'sthe'numerali lll.1.denotes aclosedWaterilevelavarieszmirinkaisesa desiredlmaximum level being indicated atI3 and the minimum level at I4. A float I5 follows the variations of theliquid level for operating a valve I6 situated in a body I I which isscrewed into the side Wall of the tank Ill. The water level in the tankstands always, even at the minimum level I4, above the valve I6.

The valve I6 controlsa passage in the body The passage I8 is opentowards the tank Ill of a bent rod 25 and whose other end is fastened,

to a wire 26. 7

Leading into the Venturi section I9 of the liquid passage I8 is anair'channel 2l-which com municates with the outside 'atmosphere and inwhich an air-check valve 28, such as a snifter valve, is provided.

When the level of the water in the tank I is low, such as at I4, thefloat I sinks from the position shown in Fig. 1 to a lower positioncorresponding to that level I4 and, by means of the connection 25, 24,pulls-the wire26-to the extreme left. The wire'26 extends into the boreof the valve I6 and is headed therein by means of a head 26' sothatthevalve l6 may move axially relative to the-wire 26 unless thelatter is pulled in the manner just described to the left, indicating alow water level in the tank. If so pulled to the left, it will keep thevalve I6 locked in its closing position so that no water can flowthrough the passage I8 and the Venturi throat I9 and no air is drawninto said throat through the air channel 21.

The chamber 20 is closed at one side by a diaphragm 29 held in place bya plug 39 which is screwed into the body I! and has a central hole 3|connecting the space behind the diaphragm 29 with the atmosphere.Thus'the diaphragm 29 is subjected at one side, the rear'side, toatmospheric pressure and at its front side to the suction pressureexisting in the chamber 29 due to the connection of the latter with thesuction side of the pump 22. With the difference of these two pressuresthe diaphragm 29 bears against the rear part of the valve I6 eitherdirectly or through the intermediary of a spring plate '32 attached tothe valve I6 near the rear end thereof. The spring plate 32 is actedupon by a spring 33 which tends to expand and thereby'to open the valveI6 whereas the diaphragm 29 tends to close it. The spring 33 is soselected that it will be able to overcome the closing effect of thediaphragm 29 upon the valve I5 when the above mentioned differencebetween atmospheric pressure and the suction pressure acting upon thediaphragm from within the chamber 20' is below a pre-set value.

34 denotes a well in which the water is at a certain level, such as thelevel 35. A Venturi-type ejector 36 is placed near the bottom of thewell 34 with its suction pipe 31 immersed in the pool 40 of the well.The jet nozzle 38 0f the ejector is connected to the pressure side ofthe pump 22 by means of a conduit 39, whereas. its delivery nozzle M isconnected to the suction side of the pump 22 by means of the suctionpipe 42. From the discharge or pressure side of the pump there leads aconduit 43 to the-bottomof the tank II].

4 Water may be withdrawn from the tank It through a pipe line 44 onopening a spigot 45.

When the pump 22 is running, it forces some water down the pipe 39 fromwhich this water discharges through the nozzle 38 of the ejector 36. InWell-known manner the jet delivered by the nozzle 38 brings upadditional water from the pool 46. The combined water stream passes thepump 22 and while part of this water goes down again to the ejector 36another part is discharged via the conduit 43 into the tank Ill, compressing the air in the space I2 of the tank. When a desired airpressure has been reached, the motor driving the pump is turned off,either by hand, or more generally by an automatic pressure operatedswitch (not shown).

Assuming that the water in the tank I 9 stands as low as the level I4,then the float I5 holds the bell crank lever 24 and the wire 26 with itshead 26 in the position shown in Fig. 2, keeping the passage I8 in thebody I! closed by the valve I6.

Therefore, no'water passes through the Venturi throat I9 of the passageI8 and, consequently, there is no suction action upon the air channel21. Regardless of the pressure (positive or negative) which may exist inthe chamber 29, the valve I8 is held locked in its closed position andcannot move as long as there is no release by the head 26' of the wire26.

When the water level in the tank rises, the float I6 rises with it,turning the bell crank lever 24 in clockwise direction and moving,thereby, the wire 26 with its head 26' to the right. The extent of thismovement of the wire 26 depends on how high the level'in the tank rises.When the water in the tank reaches the level I3, the head 26 Of the wire26 is moved to its extreme right position, which permits the valve I6 toopen fully. The movement of the wire 25 to the right does not entail initself an opening movement of the valve I6. Such movement of the wire 26merely unlocks, or preconditions, the valve I6 for an opening movement,but whether or not the valve actually opens depends upon the pressureexisting or developing in the chamber 20. This, in turn, depends on thesuction effect produced by the pump22 with the suction side of which thechamber 20 is connected. When the pump 22 starts up, it develops a verystrong suction, which may be on the order of 15 or 20 feet of water.Thus, during this starting period, the atmospheric pressure actingthrough the opening 3| in the plug 39 upon the right hand side of thediaphragm 29, which tends to keep the valve It closed, is supported bythe strong suction in the chamber 20. The spring 33 is not strong enoughto overcome the sum of these two closing forces, and the valve I6remains on its seat. There is thus no water flowing through the passageI8, I9 and no air is admitted to the system, in spite of the fact thatthe wire 26 has been moved to the right where it would not obstructopening of the valve l6, if the latter were to open. For the reasongiven, however, the valve I6 remains closed so that no air is admittedto the system at this time, that is, when the pump is exerting anexcessive suction upon thechamber 20. Admission of air at this timewould involvethe danger of so large an amount of air entering theupstarting pump that the suction thereof might be broken.

When the starting period of the pump 22 is ended and the latter assumesor approaches normal operation, its suction pressure diminishes to avalue which ordinarily is not much diflerent from the atmosphericpressure. When the algebraic .difierence. ofathe atmosphericzpressur'eiacting upon the rear .side for :the 'diaphragmtza and the.suction pressure acting .upon the :otherkside of-the diaphragm reaches aName-below a Predetermined positive value, .theiforce of rthe spring23Jacting upon thespringzplatetzattached to'the valve .i 6 becomessufiicient :to overcome the 'flexure ofthediaphragm'29:andthereby:toopen the valve IE. Now, under the staticpressure of the liquid. in the tank lllcandzthesuctionin chamber 2!],liquid flowsfrom the'tankithrough'the passage. I8, .l9. In theVenturisection 19 of this passage 18,19 the static pressurev of theliquid is reduced to a subatmospheric value. Due to the subatmosphericpressure 'in the Venturi throat is :air :is drawn through thefairpassage21 .past the check valve 28 and into said Venturi throat l9 where itmixes with i the liquid-stream so as to become finely dispersed therein.The-air-laden water passes through the chamber 211 and the conduits 2!and 42 intothe pump 22. From here part of the air-laden liquid goesdirectly through the-conduit isinto the tank In, whereas another part isforced down through-the'conduit'39-to the ejector 36 where it meetsthe-water coming from the well 34 and then is drawn up'again into thesuction side of thepump 22. In this manner a by-passisprovided'fortheadmission of finely dispersed air particlesinto-theliqu-id-system. Upon reaching the tank In the air rises to thesurface ltwill be observed that air'is drawn through the-passage '2lintothe liquidby-pass whenever, and as long as, the valve 'lfiisopen. Therate of flow of the air will depend largely upon the magnitude of thesuction created'inthe Venturithroat is by the liquid passingtherethroughfwhich suction in turnwill be the-greater thewider the valveis opens. Within the limits ofthe suction pressure of the pump 22between which the valve l6 willopen at all, the valve-opens the less thehigher the suction pressureaof the' pump22 is.

Therefore, air will always be drawn into the liquidsystem ata-properlycontrolled rate so as, on the one hand, not toendangertheproper function ofthe pump- 22 and, on-the other hand, tosecure the admittance of anample amount of air even though the suctioneffect of the pump may be relatively very low. Contrariwise, when thesuction effect of thepumpis extraordinarily high, such as during astarting-up period of the pump, the admission of air through'the by-passis cutoff just as completely aswhen the valve I6 is held locked in itsclosing positionby the head 26' of the wire 26 duetOaloW water'level'inthe tank.

While the pump 22-isworking, the-water rising in the tank Ill compressesthe air dump of the water. When the'permittedmaximum level I3 isreached, the pump is shutoff. This'may'be done,

the-automatic switch maybe adjusted sothatit.

shuts- 0ft the'pump when the-pressure-in=thetank It now, while the.

reaches 40 pounds per square inch, and starts the pump up again when thepressure :drops to 20 poundsper square inch. i

The pump being restarted, refilling of the tank takes place. If noairwould be added to'the air present above the liquid in the tank,refilling of the tankupto the level at which the withdrawal ofwaterstarted would not restore theair pressure which existed in theitankwhen the spigot was opened, on account 'of the fact thatlthe "ticularapplication,.it will be understood that the invention isapplicable'to'the control of the air contents of other pressure tanksthan water storage tanks and to other pump systems than-the one shown,and further that the particular embodiment shown in the drawing has beengiven by way of example only, since many changes, rearrangements, andmodifications of the parts shown and described hereinbefore may be madewithout departing from the spirit of the invenition or from the scope:of the appendedclaims.

WhatI claim is:

1. In combination, a body having a chamber, suction-creating meansconnected 'to said chamber, a Venturi passage in said body one end ofthe passage leading tothe chamber while the other end is connected to asupply of liquid, a.

valve adapted to prevent the flow of liquid from said passage into saidchamber, a flexible-diaphragm forming one wallof said-chamber so .as

1 to be exposed on one side to the action of said suction creatingmeans, and-bearing. against said valve under, the action of atmosphericpressure to which it is exposed on its other side, a spring tending toopen said valve, said spring being strong enough to overcome the fiexureof said diaphragm and thereby to open said'valve only if the differencebetween the two pressures acting upon the two sides of said diaphragm isbelow a predetermined value, an air channel communieating withthe'atmosphere and opening into said Venturi passage, and an air valvein said air channel for admitting air to said Venturi passage when andas long as said liquid valve is open.

2. In combination, a liquid supply, suction creating means, a body, achamber in said body connected to said suction creating means, a Venturipassage in said body communicating with said liquid supply and emptyinginto said chamber, a liquid valve between said 'Venturi passage and saidchamber, a flexible-diaphragm forming one wall of said chamber so as .tobe exposed on one side to the action of said suction creating meanswhereas its other side is exposed to atmospheric pressure, a springtending to open said 'valve, said spring extending between astationaryabutment provided in said chamber and a spring plate attached to saidvalve so as to move together with said plate, said diaphragm bearingagainst at least one of the twoparts valve and spring plate, said springbeing-strong enough to overcome the fiexure of said diaphragm andthereby to open said valve .only ifthe difierence between the twopressures acting upon the two sides of said diaphragm is belowapredetermined value, an air channel in permanent communication with theoutside atmosphere and opening into said Venturi passagaand an air valvein said air channel for admitting air to said Venturi passage when andas long 'as said liquid valve is open.

3. In combination, a body having an inlet for liquid of higher thanatmospheric pressure, a discharge outlet, a suction creating pumpattached to the discharge outlet, a passage for liquid extending fromsaid inlet to said outlet, a Venturi section in said passage wherein thestatic pressure of the liquid flowing through the passage is less thanatmospheric, a valve beyond said Venturi section adapted to close theflow through said passage, a diaphragm tending to close said valveresponsive to the diiierence between atmospheric pressure and thesuction pressure existing at said outlet, a spring capable of openingthe valve against the diaphragm pressure when said suction pressure isless than a preset amount, and an air connection from the atmosphere tosaid Venturi section permitting air to be drawn into the liquid flowingthrough said body.

4'. In a jet pump system, in combination, a well, an ejector in thewell, a pump at the top of the well, a conduit leading from the ejectorto the suction side of the pump, a conduit leading from the dischargeside of the pump to the ejector, a conduit leading from the dischargeside or the pump, a receiving tank into which said conduit leading fromthe pump discharges liquid, a by pass designed to admit finely dispersedair particles into the liquid system and leading from said tank to saidsuction side of said pump, a Venturi section in said by-pass wherein thestatic liquid pressure of the liquid flowing through the by-pass issubatmospheric, a valve beyond said Venturi section adapted to close theflow through said by-pass, a diaphragm tending to close said valveresponsive to the difference between atmospheric pressure and thesuction pressure at the pump inlet, a spring capable of opening thevalve against the diaphragm pressure when the suction is less than apre-set amount, and an air connection from the atmosphere to saidVenturi section permitting air to be drawn into the liquid flowingthrough said by-pass.

5. In a jet pump system, in combination, a well, an ejector in the well,a pump at the top of the well, a conduit leading from the ejector to thesuction side of the pump, a conduit leading from the discharge side ofthe pump to the ejector, a conduit leading from the discharge side ofthe pump, a receiving tank into which said conduit leading from the pumpdischarges liquid, a bypass designed to admit finely dispersed airparticles into the liquid system and leadin from said tank to saidsuction side of said pump, a Venturi section in said b-y-pass whereinthe static liquid pressure of the liquid flowing through the bypass issubatmospheric, a valve beyond said Venturi section adapted to close theflow through said by-pass, a diaphragm tending to close said valveresponsive to the difference between atmospheric pressure and thesuction pressure at the pump inlet, a spring capable of opening thevalve against the diaphragm pressure when the suction is less than apre-set amount, an air connection from the atmosphere to said Venturisection permitting air to be drawn into the liquid flowing through saidby-pass, and means responsive to changes in the liquid level in saidtank operatively connected with said valve for keeping said valve lockedin its closing position when said liquid level is at or below a givenheight and Q unlocking it for movement into its open position when saidlever is above said given height.

.6. An apparatus for controlling the air contents in a storage tankintowhich liquid is delivered by a pump,said apparatus comprising a storagetank, a-body having a passage communicating with the liquidspacein saidtank, a valve for opening and closing said passage, means for admittingair to said passage whenever said valve is open, means responsive tochanges in the liquid level in said tank including an elongated elementmovable relative to said valve in the direction of the axis of thelatter, said elongated element carrying a locking member extending intothe path of said valve for keeping said valve locked in its closedposition when said liquid level'is at or below a given height andunlocking it for movement into its open position when said level isabove said given height, a pump for feeding liquid to the tank, andmeansresponsive to changes in the suction developed by said pump determiningwhen said valve, when unlocked by said liquid level responsive means formovement into its open position, will actually be so moved.

'7. In combination, a body having an inlet for liquid of higher thanatmospheric pressure, a discharge outlet, a suction-creating pumpattached to the discharge outlet, a passage for liquid extending fromsaid inlet to said outlet, a Venturi section in said passage wherein thestatic pressure of the liquid flowing through the passage is less thanatmospheric, a valve beyond said Venturi section adapted to close theflow through said passage, a diaphragm tending to close said valveresponsive to the difference between atmospheric pressure and thesuction pressure existing at said outlet, a spring capable of openingthe valve against the diaphragm pressure when said suction is lessthan apre-set amount, an air connection from the atmosphere to said Venturisection permitting air to be drawn into the liquid flowing through saidbody, and an elongated element movable relative to said valve in thedirection of the axis of the latter between two end positions, saidelongated element carrying a locking member extending into the path ofsaid valve so as to keep, when in its one end position, said valvelocked in its closing position and to unlock said valve for movementinto its open position when in a position other than said one endposition. I

8. In a jet pump system, in combination, a well, an ejector in'the well,a pump at the top of the well, a conduit leading from the ejector to thesuctioncside of the pump, a conduit leading from the discharge side ofthe pump to the ejector, a conduit leading from the discharge side ofthe pump, a receiving tank into which said conduit leading from the pumpdischarges liquid, a bypass designed to admit finely dispersed airparticles into the liquid system and leading from said tank to saidsuction side of said pump, a Venturisection in said by-pass wherein thestatic liquid pressure of the liquid flowing through the by-pass issubatmospheric, a valve beyond said Venturi section adapted to close theflow through said by-pass, a diaphragm tending to close said valveresponsive to the difference between atmospheric pressure and thesuction pressure at the pump inlet, a spring capable of opening thevalve against the diaphragm pressure when the suction is less than apre-set amount, an air connection from the atmosphere to said Venturisection permitting air to be drawn into the liquid 7 flowing throughsaid by-pass, and means respon- 9 "tsive tozchanges in ithe liquid levelin'said tank ini eluding an elongated: element movable relative to "saidvalvaintthezdire'ction of the axis of the latter'gisaidielon'gatedelement carrying atlocking member extending into the path of said valvefor whose suction side is connected to'said conduit? andwhose dischargeside: is. connected to said 'ejectona closed tank, a conduit leadingfrom the discharge side of the pump into-said closed tank, a waterdelivery pipe extending out from the lower part of said tank, anapparatus permitting air to flow from the atmosphere to the suction sideof the pump, a valve in said apparatus controlling the flow of airthrough said apparatus, means responsive to the level of the water inthe tank adapted to actuate said valve, other means responsive to theamount of the suction pressure at the inlet side of the pump, bothadapted to actuate said valve to closed position.

10. In a water system, in combination, a conduit having an inletextending below the level of a body of water, an ejector nozzle in saidconduit tending to draw water up through said inlet, a pump whosesuction side is connected to said conduit and whose discharge side isconnected to said ejector, a closed tank, a conduit leading from thedischarge side of the pump into said closed tank, a water delivery pipeextending out from the lower part of said tank, means for feeding air tothe tank, comprising a conduit extending from the tank to the suctionside of the pump, a Venturi in said conduit wherein the pressure issub-atmospheric even though the pressure at the pump inlet be positive,an air inlet to said Venturi, a valve in said conduit adapted to preventthe fiow of water and air through the conduit, means responsive to thelevel of the water in the tank and other means responsive to the suctionpressure at the inlet side of said pump, both adapted to close saidvalve.

11. In combination, a tank, a body adapted to be fitted into an openingin said tank, a pipe connection to that part of the body extendingoutside of the tank, a passage having a Venturi section extendingthrough the body from within the tank to the pipe connection, an airinlet leading to the Venturi section, a valve adapted to close thepassage, means responsive to the level of the water in the tank, meansresponsive to the pressure of the fluid in the pipe connection, saidlast two means cooperating to operate said valve to permit the flow ofair into the pipe connection only when the water level in the tank isabove a set value and the fluid pressure in the connection exceeds a setvalue.

12. In a water supply system, in combination, a ieed pump, a receivingtank having air under pressure in a space above the water surface, meansadapted to admit air to the suction side of said pump only when the airspace in the tank has decreased below a preset volume and the suctionpressure at the pump entrance does not exceed a given value, comprising,a body adapted to be fastened with its inner end projecting into anopening in the wall of said tank. a recess extending into said body fromits outer end, a diaphragmclosingroifithe reces's-toform :a' chamber,

, a passage extending. from: the chamber through thebodyintolthe tank,a" Venturi contraction in said passa'ge;.ant inle-tadmitting airito saidpas- 1 sage -at the Venturi contraction, a connection air which mixed":withithe water before? reachingathe'v pump, a valve in the: chamberadapted to beimoved inward into positionto' close the flow through the'passage by said diaphragm, a

' calibrated springiresisting the inward distortion "of the diaphragm bysuctionzinthe chamber;

5 8.13, Infawvater supply system, in combination, a; ieedpump, areceivingitank havingair. under pressure in a 'spacei.-above the watersurface, means adapted .ito'r admits. air-L to the 5 suction side ofsaid pump only when the air space in the tank has decreased below apreset volume and the suction pressure at the pump entrance does notexceed a given value, comprising, a body adapted to be fastened with itsinner end projecting into an opening in the wall of said tank, a recessextending into said body from its outer end, a diaphragm closing off therecess to form a chamber, a passage extending from the chamber throughthe body into the tank, a Venturi contraction in said passage, an inletadmitting air to said passage at the Venturi contraction. a connectionfrom the chamber to the suction side of said pump enabling it to drawsome water from the tank through the Venturi and thereby to draw in airwhich is mixed with the water before reaching the pump, a valve in thechamber adapted to be moved inward into position to close the flowthrough the passage by said diaphragm, a calibrated spring resisting theinward distortion of the diaphragm by suction in the chamber, a float inthe tank, means connecting said valve to the float so that the risingfloat can close the valve independent of the diaphragm.

14. In a water supply system, in combination, a feed pump, a receivingtank having air under pressure in a space above the water surface, meansadapted to admit air to the suction side of said pump only when the airspace in the tank has decreased below a preset volume and the suctionpressure at the pump entrance does not exceed a given value, comprising,abody adapted to be fastened with its inner end projecting into anopening in the wall of said tank, a recess extending into said body fromits outer end, a diaphragm closing off the recess to form a chamber, apassage extending from the chamber through the body into the tank, aVenturi contraction in said passage, an inlet admitting air to saidpassage at the Venturi contraction, a connection from the chamber to thesuction side of said purnp enabling it to draw water from the tankthrough the Venturi and thereby to draw in air which is mixed with waterbefore reaching the pump, a valve in the chamber adapted to be movedinto position to close the flow through the passage, a float in the tankconnected to'said valve to hold said valve closed unless the water inthe tank stands above a given level, a connection between the diaphragmand the valve adapted to close the valve when the diaphragm flexesinward, a calibrated spring resisting the inward distortion of thediaphragm by the suction created by the pump.

15. An apparatus for controlling the volume of air in a storage tank towhich liquid is delivered 11' by a pump, comprising, a storage tank, apump connected to the storage tank, a body adapted to be fixed in thewall of said tank, a chamber in the body, a passage in said bodyconnecting said chamber with one end of the body, a valve adapted toopen and close the passage, a connection from the chamber to the suctionside of said pump, a Venturi connection in said passage, a connection tothe atmosphere for drawing air into said passage at the venturi wheneverthe valve is opened and liquid flows through the passage, meansresponsive to changes of the liquid level in said tank including anelement movable relative to the valve in the direction of the latter,said element carrying a locking member extending into the pathoi thevalve to keep the valve locked when said liquid level is at or below agiven height and unlocking it for movement to 7 open position when saidlevel is above said given height, and means for locking said valve whenREFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 7 2,291,746 Nelson et a1 Aug. 4,1942 2,327,601 Kent Aug. 24, 1943

